THOMPSON: ANATOMY OF MOSQUITO. 
169 
stout setae and is flanked by setose areas. Here the thin chitin 
characteristic of the ventral face of the rostrum generally, is 
strengthened by a triangular sclerite. I regard this structure as an 
epipharynx. It receives a pair of slender muscles (Raschke, ’87) 
which arise on the top of the head and probably function as retrac¬ 
tors. 
The border line and shelf-like fold already described, mark the 
boundary between the heavier chitin of the dorsal and the thinner 
chitin of the ventral face of the rostrum, above and in front. But 
on either side, near the antennae, the thicker chitin involves part 
of the ventral face of the rostrum. These inflected areas of 
heavy chitin I call the black-spot areas, because each bears a con¬ 
spicuous patch of pigment ( bits ). From either area a narrow-linear 
“ line ” of heavier chitin traverses the ventral face of the rostrum to 
strengthen the sclerite of the epipharynx. In the bay of thin 
cuticle bounded in front by the anterior shelf and border line, 
and posteriorly by the black-spot areas, lie the small, median 
palatum (pat) and the larger, lateral flabellae (ft). These are pro¬ 
tuberances, densely clothed with fine hairs, the flabellae having in 
addition a peculiar arrangement of long yellow setae. Black-pig¬ 
mented apodemes (pi. 15, fig. 31) that are continuous externally 
with the black-spot areas enter each flabella and the two flabellae 
are united by a transverse rod. To the apodemes the flabellal mus¬ 
cles (retr ft) are attached, two for each flabella, an inner and an 
outer, both retractor in function and acting simultaneously. When 
these muscles contract the seta-bearing area of the flabella is 
depressed and the setae come together in a brush whose tip points 
caudad. On their relaxation the flabellae protrude beyond the front 
of the head and the setae stand out in great yellow fans. The 
median prominence or palatum passively follows the movements of 
the flabellae, which are strictly synchronous, as far as I have 
observed. 
The mouthparts .— The mouthparts (pi. 15, fig. 29, 32) of a Culex 
wriggler consist of huge maxillae, moderate sized, toothed mandi¬ 
bles and sclerites which represent labium and hypopharynx. The 
maxillae conceal the greater part of the under surface of the rostrum. 
The palp is minute. These appendages are not joined to the head 
by definite articulations as are the mandibles, and do not move as 
freely. Within the epipharynx above, mandibles, maxillae at the 
